1. Field
The present disclosure relates generally to aircraft, and more particularly, to landing gear for aircraft. Still more particularly, the present disclosure relates to a fuselage mounted landing gear for aircraft and to a method for retracting a fuselage mounted landing gear.
2. Background
An effective landing gear design for an aircraft should provide an optimum combination of sufficient overall functional strength, a geometric arrangement for adequate ground maneuvering and landing stability, a lowest possible weight, and a lowest possible drag when retracted. On any high wing or other aircraft in which the main landing gear is not easily stored or cannot be attached to a wing of the aircraft, at least one of the above goals may be at risk. In the case of fuselage mounted landing gear configurations, for example, the low drag goal may be compromised.
An aircraft's main landing gear must be placed sufficiently outboard of the side of the body of the aircraft to enhance stability and prevent wallowing during ground maneuvers. On low wing aircraft this is usually not a problem because a gear post can be attached to the wing, outboard of the side of the body of the aircraft. When the gear is extended, the gear must be far enough out to ensure stability. On an aircraft that cannot use wing mounted landing gear, the landing gear typically must be mounted to and completely stored within the body of the aircraft.
Fuselage mounted landing gear (FMLG) designs may be heavy and cause significant drag. Typically, in order for the landing gear to be sufficiently outboard, the body frame of the landing gear is extended beyond the side of the body of the aircraft. The top of gear struts are attached to trunnions mounted to these frames. The gear assembly pivots around these trunnions and is stowed inside the body.
In order to minimize the drag associated with the increase in frontal area, a fairing is wrapped around the external structure, driving additional structural weight. Despite streamlining efforts, total drag is still dependent upon frontal area and surface area, both of which are increased by the fairings.
Large fairings increase aircraft wetted area and frontal area, and, accordingly, the parasite drag grows, which may effect the efficiency of the aircraft. Moreover, for middle wing configurations, the main landing gear fairing may become close to the lower wing surface, which may create additional interference drag.
Another feature which is typical for most current FMLG designs is that the retracted landing gear occupies bays between fuselage frames to adequately accommodate a big wheel truck. This has an effect on available internal fuselage volume, which could otherwise be used for other systems or for additional cargo space.
Therefore, it would be advantageous to have a landing gear for an aircraft that takes into account one or more of the issues discussed above, as well as possibly other issues.